FX impact x external plenum cal 22 low performance

[Powerage]

Hello everyone. I picked up a powerkit from a guy who is selling those on fb. The kit included the modified pellet probe. Barrel brass transfer port. 30Cc external plenum and hammer weight. And delrin c3. 

After installing the kit I was expecting to shoot the fx hybrid slugs at high speeds. to my surprise I didn’t gain much . Maybe 50 FPS and that was from the probe and the brass. Max speed is now 920 FPS on the hybrids. To gain that speed I have to put my reg to 150 and hammer maxed out. Lower settings give me lower speed. I tried remount everything several times. Changed the valve seat , valve o ring. Inspected the , springs, rod o rings. Everting seems fine. The only strange things is that I get a small blowback of air when I shoot trough the mag. I’m thinking it might be a the inner barrel o ring . But it looks decent . I was hoping higher speeds.. any advise. The barrel is a 600 mm slug liner. 

 

[heavy-impact]

You have to modify the valve housing for an external plenum or else the air has nowhere to go.

Ignore the roll pin mod, you just need to cut the bottom bridge off the valve housing like in the picture.

Also drill the hole where the gauge screwed into the rear block to 6mm while the valve housing is out and remove any burr left on the inside so the o-rings slide past with no damage. I use 3M pink polishing paper for deburring and polishing.

 

[Powerage]

Thank for reply. Valvehouse mod I already did. Forgot to write in my post. I removed the delrin from the gauge hole. I will try to drill it to 6 mm as well. I’m getting 900 FPS at 120 bar but have to push it to 150 to get 930. The hybrids are only 22 grain. Was expecting them to fly fast with this kit. 


I also have an impact mk2 25 cal 700 mm barrel with the “polish fx”plenum witch is so powerfull compared to this one. Pushing the 34 grain jsb to 960 at only 110 bar. 

 

[Fire_at_will]

Sounds like you may have a leak from the oring on the end of the valve pin. 

 

[spyde82]

I was shooting the nsa 23gr at 960fps with a 600mm barrel. Only mod was transfer port so you should be avle to shoot Them alot faster

 

[Powerage]

Thank for all the feedback. I check the o ring on the valve. Seems to be ok . Spyde82 that was mk1 ? 

 

[spyde82]

Thank for all the feedback. I check the o ring on the valve. Seems to be ok . Spyde82 that was mk1 ?

No mk2

 

[Powerage]

My experience is that the mk2 is pretty powerful . Especially if you do the tp and the pellet probe mod . 


my MK 1 is probably underperforming but Im starting to be out of ideas where to check 

 

[cowabunka]

You have to modify the valve housing for an external plenum or else the air has nowhere to go.

Ignore the roll pin mod, you just need to cut the bottom bridge off the valve housing like in the picture.

Also drill the hole where the gauge screwed into the rear block to 6mm while the valve housing is out and remove any burr left on the inside so the o-rings slide past with no damage. I use 3M pink polishing paper for deburring and polishing.

Other than removing the bottom bridge, any other mod needed to get the external plenum to work?

For the new MK2 with power plenum, is it worthwhile installing an additional external plenum?

 

[heavy-impact]

Other than removing the bottom bridge, any other mod needed to get the external plenum to work?



For the new MK2 with power plenum, is it worthwhile installing an additional external plenum?

1: No

2: No unless you're going to .35 caliber with a larger valve and willing to drill and thread your rear block to M14 to use an external with a higher flow rate.

The version from Poland offers greater performance in .30 caliber since it has about 15cc more capacity.

If you want the Polish plenum buy directly from Michal in Poland for $150 shipped and install it yourself. If you need free help installing it just PM me here.


AT Michał Osyda


98-300 Gaszyn, ul.Źródlana 13a


Tel. 883999733



www.airguntuning.pl

 

[BMC]

Sounds like you need a 6.5mm valve seat.

 

[heavy-impact]

Sounds like you need a 6.5mm valve seat.

A larger valve won't make as much difference in .22 caliber but you can drill the original to 1/4" (6.35mm).

 

[JamieUK]

Might be worth checking the TP and probe are aligned.

Are the slugs seating far enough in the barrel ( so past the point where the leading inner edge of the port has been flowed/ removed) ?

 

[Powerage]

Thanks for the feedback . Maybe I’ll just swap with my 22 dreamline pellet barrel to see if it makes any difference. 

 

[schlupsa]

When I felt air on my face when firing it was because the pellet probe rod had loosened itself (5 month old MK2) so far that it was pushing out the shoulder pad. Check pellet probe depth and loctite that rod.

-Steve